Big Bang Problem

[MartinM]

Thus COBE was launched to an orbit 559 miles above the earth, carrying sensitive instruments to measure the background radiation. Alas, preliminary data from COBE announced in January, show absolutely no evidence of inhomogeneity in the background radiation. It is perfectly smooth.

Nonsense. COBE did find evidence of inhomogenity, and newer instruments have mapped those inhomogenities across the sky. The pattern is nicely consistent with the predictions of modern cosmological models. Gish is either lying or incompetent.

 

[Lucretius]

Lucretius, space-time is probably both Euclidean (flat) and accelerating in its expansion. Flatness simply refers to whether "parallel" lines diverge, continue the same distance forever, or eventually meet. With the discovery of dark energy, it no longer has any real connection to the final fate of the universe.

Madarab, I think you are mistaken.

The geometry of the universe depends on the critical density of the universe. Because the universe is actually accelerating (among other observational evidence), it seems that, even with proposed dark matter, the universe does not have Critical Density (?) = 1. So ?<1. This means the global geometry of the universe is most likely hyperbolic, and non-Euclidean.

Even with Dark Energy, the Critical Density factor is still vital to discovering the shape, and therefore, the fate of the universe.

http://en.wikipedia.org/wiki/Shape_of_the_universe

 

[YellowStar]

Nonsense. COBE did find evidence of inhomogenity, and newer instruments have mapped those inhomogenities across the sky. The pattern is nicely consistent with the predictions of modern cosmological models. Gish is either lying or incompetent.

Have you got any evidence to back this up? Just wondering

 

[pantsman52]

Have you got any evidence to back this up? Just wondering

How about the official COBE site?

http://lambda.gsfc.nasa.gov/product/cobe/

The CMB was found to have intrinsic "anisotropy" for the first time, at a level of a part in 100,000. These tiny variations in the intensity of the CMB over the sky show how matter and energy was distributed when the Universe was still very young. Later, through a process still poorly understood, the early structures seen by DMR developed into galaxies, galaxy clusters, and the large scale structure that we see in the Universe today.

 

[nvxplorer]

Have you got any evidence to back this up? Just wondering

 

[Dark_Adonis]

Have you got any evidence to back this up? Just wondering

Added: DATE OF THE ARTICLE: Jun 1, 1991
When something from 1991 talks about preliminary data and it is
2005 you better believe the full data is released. Perhaps a more
recent article should be used, please don't ask how much of an idiot
I am to actually track down the article.

From: http://en.wikipedia.org/wiki/COBE#Scientific_findings
Also there are some interesting pictures of the map there

Intrinsic anisotropy of CMB

The DMR was able to spend four years mapping the anisotropy of cosmic background radiation as it was the only instrument not dependent on the dewar’s supply of helium to keep it cooled. This operation was able to create full maps of the CMB by subtracting out galactic emissions and dipole at various frequencies. The cosmic microwave background fluctuations are extremely faint, only one part in 100,000 compared to the 2.73 kelvin average temperature of the radiation field. The cosmic microwave background radiation is a remnant of the Big Bang and the fluctuations are the imprint of density contrast in the early universe. The density ripples are believed to have produced structure formation as observed in the universe today : clusters of galaxies and vast regions devoid of galaxies (NASA).

From:http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation#Experiments

Of these experiments, the Cosmic Background Explorer (COBE) satellite that was flown in 1989-1996 is probably the most famous and which made the first detection of the large scale anisotropies (other than the dipole).

This article appears to be written before the COBE data was fully digested.

Also it should be noted that WMAP has since been launched to further investigate the CMB anisotropies.
For more on WMAP: http://en.wikipedia.org/wiki/WMAP

Edit: It is suggested that archived articles be researched to check that the article(s) pertain.

 

[pantsman52]

Does this count as PWNED?

 

[TeddyKGB]

Does this count as PWNED?

No... it redefines it.

 

[MartinM]

Madarab, I think you are mistaken.

No, he's right. Take a look at Friedmann's equations:

where a is the scale factor of the Universe, p is pressure, and rho denotes the total density of the Universe, including the contribution from vacuum energy as well as from matter; that is,

The first equation determines the geometry of the Universe - if k > 0, the Universe is closed. If k < 0, the Universe is open. And if k = 0, the Universe is flat. The latter case defines the critical density:

Clearly if the total density of the Universe exceeds this value, k > 0, and if the total density falls short of this value, k < 0.

So we know how density determines geometry. The important point here is that the geometry of the Universe is fixed by the total density, including that of any vacuum energy that may exist.

 

[MartinM]

Now for acceleration. From the second equation, we see that the expansion of the Universe can only accelerate if

The matter content of the Universe can be well approximated by a pressureless dust, so in a Universe with only matter this condition can never be met, since matter density is non-negative by definition. In such a Universe, the expansion rate can never accelerate. But vacuum energy can satisfy this requirement. For the scalar fields that drive inflation,

and so we have:

which can be negative regardless of the value of rho relative to the critical density. Even an overdense, closed Universe can undergo accelerated expansion.

 

[notto]

Wonders if YellowStar will start to see why we question AIG's science and tactics.

Gish is lying or misinformed, right there in the material you posted. What does that tell you about the quality of the material to be found at AIG?

 

[MartinM]

Judging by the bullfrog saga, my money's on lying.

 

[Lucretius]

Now for acceleration. From the second equation, we see that the expansion of the Universe can only accelerate if

The matter content of the Universe can be well approximated by a pressureless dust, so in a Universe with only matter this condition can never be met, since matter density is non-negative by definition. In such a Universe, the expansion rate can never accelerate. But vacuum energy can satisfy this requirement. For the scalar fields that drive inflation,

and so we have:

which can be negative regardless of the value of rho relative to the critical density. Even an overdense, closed Universe can undergo accelerated expansion.

Could a closed universe still be Euclidean though? Wouldn't we need some type of non-Euclidean Geometry (spherical or hyperbolic, where we would have parallel lines eventually just go around in circles) to satisfy a closed universe?

I thank you for taking the time to run the equations through for me. I can't say no to the math MartinM, I am writing a refutation of Van Flandern's 10 Big Bang "problems". You seem to be a man who knows his physics. Would you care to help me edit?

 

[madarab]

I'm not sure which is worse: the fact that Gish wrote this for public consumption or the fact that so many people are so ready to buy into it and keep spewing it out.

 

[MartinM]

Could a closed universe still be Euclidean though?

No. The parameter k describes the geometry of the Universe, and is completely determined by the total density. An overdense Universe is always spherical, underdense always hyperbolic, and critical always flat. The presence of vacuum energy doesn't alter that correspondence, since it's just an additional term in the density. What it does is alter the correspondence between geometry and the ultimate fate of the Universe.

I thank you for taking the time to run the equations through for me. I can't say no to the math MartinM, I am writing a refutation of Van Flandern's 10 Big Bang "problems". You seem to be a man who knows his physics. Would you care to help me edit?

Certainly

 

[Lucretius]

No. The parameter k describes the geometry of the Universe, and is completely determined by the total density. An overdense Universe is always spherical, underdense always hyperbolic, and critical always flat. The presence of vacuum energy doesn't alter that correspondence, since it's just an additional term in the density. What it does is alter the correspondence between geometry and the ultimate fate of the Universe.

Okay, good, then I thought correctly. From my reading, this universe is underdense, and would therefore have hyperbolic geometry. Even with all the proposed dark matter it is still underdense (or so I read).

Anyways, I will PM that paper to you (in two parts, too big)

 

[MartinM]

Okay, good, then I thought correctly. From my reading, this universe is underdense, and would therefore have hyperbolic geometry. Even with all the proposed dark matter it is still underdense (or so I read).

The density of matter is far below critical - about 30% of critical. But there's a large contribution from dark energy which pushes the total density very near critical - first data release from WMAP suggested a total density of 1.02 times critical, plus or minus .02

Anyways, I will PM that paper to you (in two parts, too big)

I'll get back to you as soon as I can

 

[YellowStar]

Wonders if YellowStar will start to see why we question AIG's science and tactics.

Gish is lying or misinformed, right there in the material you posted. What does that tell you about the quality of the material to be found at AIG?

The information was NOT from AIG.

 

[notto]

The information was NOT from AIG.

Sorry, my bad. ICR. It's hard to keep the pseudoscientific ministry organizations straight.

 

[larry lunchpail]

interesting:

http://www.sciencedaily.com/releases/2005/09/050902065550.htm#richards